Situation: You have a computer which you want to connect to your already existing network infrastructure.
Problem: You don’t have any switch or hub available only a network card and an already connected computer.
Solution: Use bridging. Its just two clicks away… ok, not really - I don’t like clicking over ssh ;-)
So what I’ll tell you now is what I’ve learned from: http://www.barmasse.org/linux/praxishilfe/ubuntu/virtualbox.html and http://ubuntuforums.org/showthread.php?t=132515 (post from user “woedend”).
Open the file /etc/network/interfaces as root and add the lines:
auto br0 iface br0 inet dhcp bridge_ports eth0 eth1
Then install the package bridge-utils and type as root:
Your DHCP server must be configured to give the br0 interface an IP address. After that you can do everything with your external connected computer as if it where connected directly.